The present invention relates to one or more metal salts containing a mixture of aromatic and/or aliphatic phosphorodithioic acids. More specifically, the present invention relates to such metal salts which are oil-soluble and can be employed in the lubrication of at least internal combustion engines.
Metal salts of phosphorodithioic acids have been utilized as lubricant additives for inhibiting corrosion and oxidation as well as improving extreme pressure and anti-wear properties.
Various phosphorodithioic acids and their derivatives are known.
Romanian Patent 75,578 relates to bis(C.sub.3-20 alkylphenyl) phosphorodithioates and to zinc salts thereof.
Chem. Abstract 102:81334m (Issue 6, 1985) relates to the distribution of products of P.sub.2 S.sub.5 with alcohols.
European Patent Application 0,024,146 relates to zinc dihydrocarbyl dithiophosphates wherein the hydrocarbyl compound includes alkyl, alkenyl, aryl, aralkyl, alkaryl and cycloaliphatic groups. These compounds are utilized in combination with copper containing lubricants.
A paper presented at the Sep. 7-12, 1969, American Chemical Society, Division of Petroleum Chemistry, Inc., meeting at New York City, by Liston et al of Chevron Corporation, relates to various types of dihydrocarbon phosphorodithioic acids and salts thereof. The alcohols utilized in making the salts can have at least two carbon atoms and generally five or more.
A paper presented at the S.A.E., Feb. 28-Mar. 4, 1977, Detroit meeting by Pless and Rodgers "Cam and Lifter Wear as Affected by Engine Oil ZDP Concentration and Type" relates to protection from excess wear by predominately alkyl ZDP instead of aryl ZDP.
U.S. Pat. No. 2,344,393 to Cook relates to metal dithiophosphates having one or more long chain alkyl groups to render them sufficiently soluble in lubricating oils. Moreover, it recognized that the zinc salt of diamylphosphorodithioic acid was oil-soluble.
U.S. Pat. No. 2,480,673 to Reiff relates to reacting a hydroxyaromatic compound with P.sub.2 S.sub.5 and thereafter treating the product with finely divided zinc. The amount of zinc utilized, however, was small and related to removing impurities as generally opposed to forming a salt.
U.S. Pat. No. 2,552,570 to McNab relates to dihydrocarbyl phosphorodithioic acids wherein the hydrocarbon group can be either aliphatic or aromatic and contain a total of 10 carbon atoms in the combined aliphatic groups, whether or not attached to an aromatic nucleus.
U.S. Pat. No. 3,000,822 to Higgins relates to zinc salts of a mixture of dialkyl phosphorodithioic acids wherein the alkyl groups comprise a mixture of lower molecular weight primary aliphatic hydrocarbon radicals having less than five carbon atoms and higher molecular weight primary aliphatic hydrocarbon radicals having at least five carbon atoms.
U.S. Pat. No. 3,190,833 to Rhodes relates to oil-soluble metal phosphorodithioates which contain a total of at least 7.6 aliphatic carbon atoms per atom of phosphorus. To improve the oil-solubility of the metal salts, they are reacted with up to about 0.75 mole of an epoxide.
U.S. Pat. No. 3,306,908 to LeSuer relates to Group II metal phosphorodithioates having substantially hydrocarbon radicals.
U.S. Pat. No. 3,318,808 to Plemich discloses that higher carbon containing alkyl groups of above four carbon atoms enhance oil-solubility. The patent also teaches the combination of C.sub.4 and lower primary and/or secondary alcohols with C.sub.5 and above alcohols.
U.S. Pat. No. 3,346,493 to LeSuer also relates to Group II metal hydrocarbon phosphorodithioates.
U.S. Pat. No. 3,352,949 to Kawahara relates to certain thioesters of dithiophosphoric acid as motor fuel additives.
U.S. Pat. No. 3,361,668 to Weise relates to a process for preparing an O,O'-diester of phosphorodithioic acid by reacting phosphorus pentasulfide with a mixture of a monohydroxy alcohol or phenol and an alkyl amine, cycloalkylamine or heterocyclic amine.
U.S. Pat. No. 3,736,110 to Ownston relates to rust-inhibitors and more particularly to organic imidazoline salts of mono- and dicresylic phosphates.
U.S. Pat. No. 3,843,530 to Niedzielski relates to preparing non-crystalline mixtures of basic or mixed basic and neutral zinc salts of dialkyldithiophosphates containing from 1 to 13 carbon atoms in the alkyl group. The mixtures of the zinc salts contain from 4 to 13 different alkyl groups, have an average carbon content of 3.5 to 4.5, and contain at least 12% by weight of zinc.
U.S. Pat. No. 3,929,653 to Elliott relates to certain dithiophosphate compounds which are useful as additives. It furthermore relates to a process of reacting a di(organo)dithiophosphoric acid and a monocyclic, non-conjugated olefin containing from 8 to 12 carbon atoms . and at least two ethylenically unsaturated double bonds in the ring, and optionally bearing one or more alkyl, alkoxy or hydroxy groups on the ring.
U.S. Pat. No. 4,085,053 to Caspari relates to a process for manufacturing metal dithiophosphates, and metal dithiophosphate compositions. The alcohol often used is an alkyl alcohol.
U.S. Pat. No. 4,105,571 to Shaub relates to a storage stable lubricating composition having improved anti-wear properties provided by a base oil composition containing an additive combination of (1) a zinc dihydrocarbyl dithiophosphate, (2) an ester of a polycarboxylic acid and a glycol, and (3) an ashless dispersant.
U.S. Pat. No. 4,113,634 to Sabol relates to the manufacture of metal diaryl dithiophosphates by reacting P.sub.2 S.sub.5 with a hydroxyaryl compound to form a dithiophosphoric acid and neutralizing said acid with metal in the presence of a promoter, said promoter comprising dialkyl dithiophosphoric acid.
U.S. Pat. No. 4,306,984 to Yamaguchi relates to a procedure for rendering oil insoluble metal C.sub.2 -C.sub.3 dialkyl dithiophosphates oil-soluble by forming a complex between the dithiophosphate and an alkenyl or alkyl mono- or bis-succinimide.
U.S. Pat. No. 4,466,895 to Schroeck relates to certain metal salts of one or more dialkylphosphorodithioic acids wherein the alkyl groups, the total number of carbon atoms per phosphorus atom and the like fall within specific ranges.